Potentially fatal Legionella and Listeria infections are the latest opportunistic infections to be added to the boxed warning for medications that block tumor necrosis factor (TNF). The US Food and Drug Administration (FDA) announced that it is requiring the labels of all drugs in this class to be updated to reflect this risk.

TNF blockers, which include infliximab, etanercept, adalimumab, certolizumab pegol, and golimumab, are used to treat such diseases as Crohn disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, plaque psoriasis, and juvenile idiopathic arthritis. These drugs suppress immune function, and their labels already bear warnings about the risk of opportunistic infections caused by bacteria, including mycobacteria, fungi, and viruses such as hepatitis B.